The present invention relates to systems for and methods of pouring concrete slabs and, more specifically, to such tools and methods that increase the likelihood that the slab will be flat and at a predetermined vertical level.
Buildings are often designed to incorporate at least one level having a floor that is on or below the grade of the ground around the building. Such floors are commonly fabricated of concrete that is poured on site; when poured, this type of concrete floor is commonly referred to as a slab.
A concrete slab must be worked on site to obtain a flat surface appropriate for use as a floor or which can be covered by a floor covering such as a carpet. To obtain a flat surface, an elongate member having a straight edge is moved back and forth over the surface of the wet concrete such that the straight edge forms a flat surface. Normally, the elongate member is a piece of wood referred to as a screed board.
While the use of a screed board can result in the formation of a concrete slab having a flat surface, the screed board does not necessarily yield a level surface. To obtain a surface that is both flat and level, the ends of the screed board must be supported at known vertical locations.
In practice, a foundation is initially formed of reinforced concrete to transfer the loads of the walls, upper floors, roof, and building contents to the ground. The foundation comprises a short vertical foundation wall portion that extends upwardly from a footing that is wider than the wall portion. A mark or chalk line is then formed on the foundation wall to define the level of the upper surface of the concrete slab. Concrete is then poured within a pour area defined by the foundation and worked with the screed board such that the upper surface thereof lies in the same horizontal plane as the chalk line on the foundation wall.
If the pour area defined by the foundation is sufficiently small, the screed board may extend across the pour area from one portion of the foundation wall to another portion thereof. In other cases, the screed board will not be able to extend completely across the pour area. In such cases, a horizontal support screed support bar is provided within the pour area to support one end of the screed board.
In either case, any end of the screed board adjacent to a foundation wall is supported by what is referred to as a shoulder. The shoulder is a narrow band of concrete that extends around the perimeter of the foundation.
In addition, a slab will often be poured around obstructions such as pipes, conduit, columns, and the like. The screed board cannot be used in these locations because of these obstructions.
Ideally, the shoulder and areas around obstructions are worked by hand using what is referred to as a hand float such that the shoulder is flat, level, and in the same vertical plane as the chalk line on the foundation wall or around the obstruction.
In practice, however, the use of a hand float to obtain a flat surface at the desired vertical level requires substantial skill. If the person using the hand float is not skilled, the edge of the shoulder closely adjacent to the foundation wall or obstruction may be at the same vertical level as the chalk line on the foundation wall but may slope upwards or downwards away from the foundation wall.
Conventionally, a carpenter""s level is used to help ensure that the shoulder is flat and level with the chalk line, but the use of a carpenter""s level is time consuming and only indicates that a narrow strip of the shoulder is flat and level with the chalk line.
If any portion of the shoulder is not flat and level with the chalk line, the working edge of the screed board will not be horizontal and within the vertical plane defined by the chalk line. Accordingly, the actual level of the upper surface of the concrete slab as formed by a mis-aligned screed board will deviate from the desired level of the upper surface of the concrete slab.
If the upper surface of the concrete slab deviates from the desired level, a number of problems may result. First, the resulting floor will not be flat and level. Second, the actual amount of concrete used will be greater than or less than the predicted amount. These and other problems create the need for improved tools, systems, and methods of pouring concrete slabs.
A professional patentability search conducted on behalf of the applicant turned up the following U.S. patents.
All of the patents in the table set forth above incorporate a bubble or spirit level into the handle of a tool of some sort. The patents to Sebastiani, Billings, Kuhar, and Lawrence depict and describe masonry tools having a spirit or bubble level incorprated into a handle thereof. None of these tools relate to hand floats for working the shoulder of a concrete slab. In contrast, these tools are specialized tools for laying bricks and, in particular, to working mortar between bricks in a vertical brick wall. The problems faced when building a brick wall are significantly different from those of pouring concrete as described above. Accordingly, the Sebastiani, Billings, Kuhar, and Lawrence patents do not disclose, teach, or suggest improved tools and/or methods for pouring flat and level concrete slabs.
The Barth and Pfouts patents relate to a ditch digging tool and a file with a spirit or bubble level incorporated therein and thus are less relevant than the patents described above.
A hand float for forming a concrete slab. The hand float comprises a substantially rectangular float member, a handle member, first and second screw members that attach the handle member to the float member, and a leveling device attached to the handle member. he user of the hand float grasps the handle member to work the concrete slab before the slab is cured. The user of the hand float views the leveling device while working the concrete slab to ensure that the portion of the slab being worked is substantially flat and substantially at a desired level.
The present invention may also be embodied as a method of forming a concrete slab comprising the following steps. First, a foundation defining a pour area is formed. A mark is formed on the foundation defining a desired level of the concrete slab. A shoulder portion of the concrete slab is then poured. A hand float assembly having a handle member, a float member, and a leveling device is used to work the shoulder portion of the concrete slab while viewing the leveling device and the mark on the foundation such that an upper surface of the shoulder portion is substantially flat and substantially at the same vertical level as the desired level of the concrete slab. The main portion of the concrete slab is then poured within the pour area. A first end of a screed board is supported on the shoulder portion of the concrete slab, and the screed is moved to work the main portion of the concrete slab such that the main portion of the concrete slab is substantially flat and substantially at the same vertical level as the desired level of the concrete slab.